Multi-die integrated circuits (ICs) are a class of ICs in which multiple dies are placed within a single package. A multi-die IC also can be referred to as a “system in a package” or “SiP.” A multi-die IC can include circuit structures that allow the dies to communicate with one another within the single package at faster speeds than would be attainable were the dies to be implemented as separate ICs or as individual IC packages mounted on a printed circuit board.
Creating a mask set for a modern integrated circuit is a costly endeavor. A “mask set” refers to electronic data that defines the geometry for the lithography steps of semiconductor fabrication. Each physical mask that is generated is referred to as a “photomask.” The phrase “mask set” refers to the collection of such photomasks required to make a particular die.
Since each die requires a mask set, one can see that the photomask cost for a multi-die IC can far exceed the photomask cost for a single die IC. The additional cost extends to the situation in which different variations (e.g., product lines or families) of the multi-die IC are developed. Typically, the creation of additional product lines for multi-die ICs involves switching one or more dies of the multi-die IC in favor of one or more other alternative dies, e.g., of larger or smaller capacity depending upon the product line requirements. Unfortunately, the need to generate a mask set for each die used in creating a multi-die IC product family can be cost prohibitive.